Ethnicity is an important determinant of athletes' cardiovascular adaptation. Black adolescent and adult athletes exhibit a left ventricular (LV) hypertrophy with a concentric remodelling higher than their Caucasian counterparts. Scant data, however, are available on race-related differences in hemodynamic response of adolescent athletes to exercise and its relation with heart remodelling. We evaluated if race-specific, sport-related structural and electrical remodelling in adolescent athletes of Caucasian and African ethnicity exclusively depends on race itself rather than on different cardiovascular responses to physical exercise.We examined 90 adolescent athletes, 60 Caucasian (WA) and 30 Black (BA). All participants underwent thorough clinical, echocardiographic and stress test evaluations.BA had greater indexed LV mass (LVM/BSA) with increased relative wall thickness (RWT) implying a concentric remodelling. BA showed higher systolic blood pressure (SBP) compared to WA during the whole exercise test. ECG data showed that BA vs WA had a significant shorter QRS duration in each step considered with a significant greater QT dispersion. BA reached a higher relative pressure peak as compared to WA. RWT was strongly influenced by ethnicity and less by SBP at peak of exercise (PE), although LVM/BSA was significantly related to SBP at PE and just marginally to age and not significantly to race.Black adolescent athletes showed higher SBP during all steps of exercise associated to a different trend. Ethnicity was the main determinant of RWT, suggesting that LV geometry is principally race-related rather than influenced by a different hemodynamic profile to physical activity.